[M T]

I wonder whether Russia could undertake a new invasion within the next 4 years. At that point, the leadership of the US has a good chance of changing and its commitment to NATO may change.(*)

Granted, the world has seen how fickle the US can be and needs to be better prepared for that fickleness. 
 
(*)This is assuming the US continues as it has for nearly 250 years.

Is the U. S. fickle, or is it just one guy? Have we been fickle in the past? We answered the bell multiple times in the last century.

The US, with its 4-year cycle, may change by 180 degrees on any 4-year boundary.  In this cycle, there was a dramatic change

[M T]

I wonder whether Russia could undertake a new invasion within the next 4 years. At that point, the leadership of the US has a good chance of changing and its commitment to NATO may change.(*)

Granted, the world has seen how fickle the US can be and needs to be better prepared for that fickleness. 
 
(*)This is assuming the US continues as it has for nearly 250 years.

Is the U. S. fickle, or is it just one guy? Have we been fickle in the past? We answered the bell multiple times in the last century.

The US, with its 4-year cycle, may change by 180 degrees on any 4-year boundary.  In this cycle, there was a dramatic change